1. ECE 6160: Advanced Computer Networks Network Management Instructor: Dr. Xubin (Ben) He Email:[email_address] Tel: 931-372-3462 Slides are adapted from the original slides developed by Kurose and Ross. All material copyright 1996-2007 J.F Kurose and K.W. Ross, All Rights Reserved

2. Network Management

introduction to network management

• motivation

• major components

Internet network management framework

• MIB: management information base

• SMI: data definition language

• SNMP: protocol for network management

• security and administration

presentation services: ASN.1

3. outline

What is network management?

Internet-standard management framework

• Structure of Management Information: SMI

• Management Information Base: MIB

• SNMP Protocol Operations and Transport Mappings

• Security and Administration

4. What is network management?

autonomous systems (aka network):100s or 1000s of interacting hardware/software components

other complex systems requiring monitoring, control:

• jet airplane

• nuclear power plant

• others?

" Network managementincludes the deployment, integrationand coordination of the hardware, software, and humanelements to monitor, test, poll, configure, analyze, evaluate,and control the network and element resources to meet thereal-time, operational performance, and Quality of Servicerequirements at a reasonable cost." 5. Infrastructure for network management managed device managed device managed device managed device network management protocol definitions: managed devicescontain managed objectswhosedata is gathered into a Management Information Base (MIB) managing entity agent data agent data agent data agent data managing entity data 6. Network Management standards

OSI CMIP

Common Management Information Protocol

designed 1980s:theunifying net management standard

too slowly standardized

SNMP: Simple Network Management Protocol

Internet roots (SGMP)

started simple

deployed, adopted rapidly

growth: size, complexity

currently: SNMP V3

de factonetwork management standard

7. outline

What is network management?

Internet-standard management framework

• Structure of Management Information: SMI

• Management Information Base: MIB

• SNMP Protocol Operations and Transport Mappings

• Security and Administration

ASN.1

8. SNMP overview: 4 key parts

Management information base (MIB):

• distributed information store of network management data

Structure of Management Information (SMI):

• data definition language for MIB objects

SNMP protocol

• convey managermanaged object info, commands

security, administration capabilities

• major addition in SNMPv3

9. SMI: data definition language

Purpose:syntax, semantics of management data well-defined, unambiguous

base data types:

• straightforward, boring

OBJECT-TYPE

• data type, status, semantics of managed object

MODULE-IDENTITY

• groups related objects into MIB module

Basic Data Types INTEGER Integer32 Unsigned32 OCTET STRING OBJECT IDENTIFIED IPaddress Counter32 Counter64 Guage32 Time Ticks Opaque 10. SNMP MIB OBJECT TYPE: OBJECT TYPE: OBJECT TYPE: objects specified via SMI OBJECT-TYPEconstruct MIB module specified via SMIMODULE-IDENTITY (100 standardized MIBs, more vendor-specific) MODULE 11. SMI: Object, module examples

OBJECT-TYPE: ipInDelivers

MODULE-IDENTITY: ipMIB

ipInDelivers OBJECT TYPE SYNTAXCounter32 MAX-ACCESSread-only STATUScurrent DESCRIPTION The total number of inputdatagrams successfullydelivered to IP user- protocols (including ICMP) ::= { ip9} ipMIB MODULE-IDENTITY LAST-UPDATED 941101000Z ORGANZATION IETF SNPv2 Working Group CONTACT-INFO Keith McCloghrie DESCRIPTION The MIB module for managing IP and ICMP implementations, but excluding their management of IP routes. REVISION 019331000Z ::= {mib-2 48} 12. MIB example: UDP module Object IDNameTypeComments 1.3.6.1.2.1.7.1UDPInDatagramsCounter32total # datagrams delivered at this node 1.3.6.1.2.1.7.2UDPNoPortsCounter32# underliverable datagrams no app at portl 1.3.6.1.2.1.7.3UDInErrorsCounter32# undeliverable datagrams all other reasons 1.3.6.1.2.1.7.4UDPOutDatagrams Counter32# datagrams sent 1.3.6.1.2.1.7.5udpTable SEQUENCEone entry for each port in use by app, gives port # and IP address 13. SNMP Naming

question:how to name every possible standard object (protocol, data, more..) in every possible network standard ??

answer:ISO Object Identifier tree:

• hierarchical naming of all objects

• each branchpoint has name, number

1.3.6.1.2.1.7.1 ISO ISO-ident. Org. US DoD Internet udpInDatagrams UDP MIB2 management 14. OSIObjectIdentifierTree Check outwww.alvestrand.no/harald/objectid/top.html 15. SNMP protocol

Two ways to convey MIB info, commands:

Managed device response Managed device trap msg request/response mode trap mode agent data managing entity agent data managing entity request 16. SNMP protocol: message types GetRequest GetNextRequest GetBulkRequest Mgr-to-agent: get me data (instance,next in list, block) Message type Function InformRequest Mgr-to-Mgr: heres MIB value SetRequest Mgr-to-agent: set MIB value Response Agent-to-mgr: value, response toRequest Trap Agent-to-mgr: inform manager of exceptional event 17. SNMP protocol: message formats 18. SNMP security and administration

encryption:DES-encrypt SNMP message

authentication:compute, sendMIC(m,k): compute hash (MIC) over message (m), secret shared key (k)

protection against playback:use nonce

view-based access control

• SNMP entity maintains database of access rights, policies for various users

• database itself accessible as managed object!

19. outline

What is network management?

Internet-standard management framework

• Structure of Management Information: SMI

• Management Information Base: MIB

• SNMP Protocol Operations and Transport Mappings

• Security and Administration

The presentation problem: ASN.1

20. The presentation problem

Q:does perfect memory-to-memory copy solve the communication problem?

A:not always!

problem:different data format, storage conventions struct { char code; int x; } test; test.x = 256; test.code=a test.code test.x test.code test.x host 1 format host 2 format a 00000001 00000011 a 00000011 00000001 21. A real-life presentation problem: aging 60shippie 2007 teenager grandma 22. Presentation problem: potential solutions

1.Sender learns receivers format. Sender translates into receivers format. Sender sends.

• • • real-world analogy?

• • • pros and cons ?

2.Sender sends. Receiver learns senders format. Receiver translate into receiver-local format

• • • real-world-analogy

• • • pros and cons?

3.Sender translates host-independent format. Sends. Receiver translates to receiver-local format.

• • • real-world analogy?

• • • pros and cons?

23. Solving the presentation problem

1.Translate local-host format to host-independent format

2.Transmit data in host-independent format

3.Translate host-independent format to remote-host format

aging 60shippie 2007 teenager grandma 24. ASN.1: Abstract Syntax Notation 1

ISO standardX.680

• used extensively in Internet

defined data types , object constructors

• like SMI

BER: Basic Encoding Rules

• specify how ASN.1-defined data objects to be transmitted

• each transmitted object has Type, Length, Value (TLV) encoding

25. TLV Encoding

Idea:transmitted data is self-identifying

• T :data type, one of ASN.1-defined types

• L :length of data in bytes

• V :value of data, encoded according to ASN.1 standard

1 2 3 4 5 6 9 Boolean Integer Bitstring Octet string Null Object Identifier Real Tag Value Type 26. TLVencoding:example V alue, 5 octets (chars) L ength, 5 bytes T ype=4, octet string V alue, 259 L ength, 2 bytes T ype=2, integer 27. Network Management: summary

network management

• extremely important: 80% of network cost

• ASN.1 for data description

• SNMP protocol as a tool for conveying information

Network management: more art than science

• what to measure/monitor

• how to respond to failures?

• alarm correlation/filtering?

28.

Bandwidth, throughput, latency

Bandwidth utilization

• particularly important for ustomers

• A common cause of performance problems

Packets per second

Round Trip Time (RTT)

• It's a good measurement for long-term trend analysis

Backbone packet loss

• Reach-ability -- Why is packet loss occurring?

Circuit Performance -- How are our carriers doing?

Performance: basic measurements 29. Measurement tools:BW and Throughput

Bing : determines the real (raw, as opposed to available or average) throughput on a link by measuring ICMP echo requests roundtrip times for different packet sizes for each end of the link.

bprobe/cprobe : estimates the maximum possible bandwidth along a given path. cprobe estimates the current congestion along a path. Currently these tools rely on two features of the IRIX operating system for SGI hardware.

Netperf : Netperf is a benchmark that can be used to measure the performance of many different types of networking. It provides tests for both unidirecitonal throughput, and end-to-end latency.

nettimer : nettimer is useful for measuring end-to-end network performance.

ttcpandnttcp : classic throughput benchmark or load generator.

30. Measurement Tools: Forward path probes

ping

Pingplotter : visual version of ping

Traceroute : Directs a packet to each router along a path without actually knowing the path, by setting the IP TTL field from 1 to n until the ultimate destination is reached. Upon receiving a packet with an expired (0) TTL, the hop generates an ICMP Time Exceeded response back to the source, thus identifying the hop and its round trip delay. Each UDP packet is sent to a probably-unused port, so when the destination receives the packet it responds with ICMP Port Unreachable.

Xtraceroute : Graphical traceroute.

traceroute: Univ. of Arizona to Tennessee Tech 31. Measurement tools: Link utilization

IPTraf : IPTraf is a console-based network statistics utility for Linux. It gathers a variety of figures such as TCP connection packet and byte counts, interface statistics and activity indicators, TCP/UDP traffic breakdowns, and LAN station packet and byte counts.

Iperf : Iperf is a tool to measure maximum TCP bandwidth, allowing the tuning of various parameters and UDP characteristics. Iperf reports bandwidth, delay jitter, datagram loss.

Tcpdump : Stable, mature, canonical portable packet collector.

32. One-way Availability/Latency Tests

Echoping : Echoping is a utility for measuring TCP/UDP latency by sending to an arbitrary (default 'echo') port. It includes support for testing HTTP query latency.

Fping : A ping variant suitable for use in scripts. fping will issue ICMP echo requests to a list of hosts in round-robin fashion. fping output is meant to be parsed by scripts.

Gnuplotping : Pings multiple hosts in parallel, with graphical display (gnuplot) of delay distribution.

Imeter : Imeter is a series of scripts that supports collection, analysis, and web-displayed graphs of long-term ping data.

33. References:

NLANR:http:// dast.nlanr.net /NPMT/

A Compendium of Network Performance Measurement Resourcesby Kai Chen

Internet Protocol Performance Metrics

Introduction to Network Performance Measurementby Daniel McRobb

Network Performance Measurement and Analysis -- Part 1: A Server-Based Measurement Infrastructureby Y. Thomas Hou, Yingfei Dong, Zhi-Li Zhang

NIMI - A System for Flexible Network Performance Measurementby A.Adams and M.Mathis